This year, Gartner says, digital music downloads will be a $6.3 billion business. Last year, CDs brought in $15 billion, significantly more than downloads. Next year, expect digital music to hit $6.8 billion.

And even five years from now, CDs will still lead the pack. Gartner estimates CD sales in 2015 will be about $10 billion, while downloads will trail at $7.7 billion.

Of course, the story here is growth, but as is typical of Internet-based market disruption, the new revenue streams aren’t increasing fast enough to make up for the decline in the old ones. That means music industry executives get to trade in their Lamborghinis every nine months instead of every six, which must just be hell.

Here’s one more surprising stat: Ringtones have become a $2.1 billion business, and while they’re declining, they’ll remain lucrative through 2015, bringing in an estimated $1.4 billion by then.

If you’re reading this, you probably haven’t paid for a ringtone since 2007, and you probably don’t know anyone who does. But there it is, generating two-point-one-billion dollars.

Yeah. I’ve never paid for a ringtone. I roll my own, so I can pick just the right part of Nine Inch Nails’ “Head Like a Hole” to hear when someone calls from the workplace:

The geekerati doesn’t buy ringtones, but there are a lot of normal people – likely with feature phones – who’d rather shell out a couple of bucks for a 10-second audio clip than learn how to edit the song files they’ve already paid for.

I quit buying music in physical format long ago, but how about you? Are you still buying CDs? Do you buy ringtones? Take the poll and sound off in the comments.

Note: There is a poll embedded within this post, please visit the site to participate in this post’s poll.

Update: Commenter Walt Stone points us to this item on Side-Line, a music news site, that quotes industry sources as saying the CD format is targeted for extinction by the major labels next year.

You read it well. The major labels plan to abandon the CD-format by the end of 2012 (or even earlier) and replace it with download/stream only releases via iTunes and related music services. The only CD-formats that will be left over will be the limited edition ones, which will of course not be available for every artist. The distribution model for these remaining CD releases would be primarily Amazon which is already the biggest CD retailer worldwide anyhow.

3 weeks ago we heard it for the first time and since then we have tried getting some feedback from EMI, Universal and Sony. All declined to comment.

Given that Gartner indicates CDs will still be bringing in the lion’s share of music revenues in 2012, the Side-Line report doesn’t make much sense. Then again, we are talking about the music business here . .